The embodiments described herein relate generally to hydraulic fracturing methods and well casing plugs.
Fracture stimulation, a known practice in the oil and gas industry, may be used to increase the production of hydrocarbons from wells, such as in lower quality reserves. Known practices include forming a well bore in a subterranean formation and inserting a well casing in the well bore. Horizontal well bores may be formed to increase the extent to which a single well bore may reach desired regions of a formation. Horizontal wells as a percentage of newly drilled wells continue to rise. Multiple fracture stages may be implemented in a single well bore to increase production levels and provide effective drainage. Perforations in sections of a well casing allow fracturing fluid at high pressure to initiate and then propagate a fracture in the formation during each stage. A proppant included in the fracturing fluid may lodge in the fracture to keep it propped open after fracturing, increasing conductivity. For effective fracturing, one section may be fractured at a time by hydraulically isolating other perforated sections. Inserting a mechanical isolation plug, sometimes called a bridge plug, may selectively isolate sections not intended for fracturing.
Placing of bridge plugs in a horizontal well casing may involve increased manipulation and time in comparison to a vertical well casing. Consequently, so-called “sand plugs” have been used to reduce time and costs for horizontal well casing. A sand plug may be formed by using a placement apparatus, such as coiled tubing or a jointed pipe string, to position an elevated concentration of sand and/or proppant provided at the end of the fracturing fluid. The high concentration of sand and/or proppant screens out against the fractures and begins to bridge off. The sand continues to bridge off against the perforations in the well casing and, eventually, bridges of against itself, creating a sand plug. A rise in pressure indicates that a proper sand plug has been formed within the well casing.
However, forming a sand plug within a horizontal well casing may present challenges due to the variety of circumstances encountered in fracture stimulation processes. Accordingly, further advancement in methods and materials for forming sand plugs may be of benefit.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.